Applicants' invention relates generally to number portability in telecommunications systems and, more particularly, to techniques for providing number portability towards Internet service providers.
Number portability in telecommunication systems typically permits end users (i.e., mobile subscribers) to retain the same telephone numbers whenever the end users change from one telecommunication service provider/operator domain to another telecommunication service provider/operator domain. Without number portability, service providers will be unable to accommodate the relocation of a mobile subscriber from one service provider to another without changing the subscriber's directory telephone number.
Changing a directory telephone number in the event of relocation of a subscriber occasions expense and effort for both the subscriber and the telecommunications provider. For the provider, it is an expensive process to administer the changes of directory telephone numbers when a subscriber relocates from one area to another. The administration required by the provider includes both efforts to define available new numbers in the new location and to update the existing directory. The relocated subscriber also incurs expense in providing notice of the new directory number to potential callers (friends and business contacts). If such notice is not provided or retained by the potential callers, calls may not be placed to the relocated subscriber. Loss of calls to a relocated subscriber can result in loss of social or business opportunity. Thus, number portability is advantageous in that it permits relocated mobile subscribers, who have changed service providers, to receive calls that otherwise might be directed to the wrong service provider and therefore would be lost.
For an understanding of number portability, a conventional telecommunications network 10 is shown in FIG. 1 and is described below. Network 10 includes a set of service provider domains 20A-20C and 20F. Three of the domains (particularly domains 20A-20C) are mobile telecommunications domains serving mobile stations; domain 20F serves fixed stations. In the illustrated network, domain 20F can be of a network type such as a public switched network (PSTN) or integrated services digital network (ISDN), for example. At least some of the areas served by domains 20 can be, and likely are, geographically coextensive. Some of the domains 20 may also be served by differing service providers, e.g., different telecommunications operating companies.
Fixed station domain 20F includes at least one local exchange 22F. Local exchange 22F is connected to a plurality of fixed subscriber stations, only one of which (subscriber 24) is shown in FIG. 1. Local exchange 22F is connected either directly or ultimately (e.g., via transit exchanges) to a gateway exchange or gateway node 26F. Gateway node 26F is connected to a database 30F. Database 30F is, in turn, connected (e.g., for updating and maintenance purpose) to a service management system 32F.
Mobile telecommunications domains 20A-20C each have respective gateway nodes 26A-26C, each of which takes the form of gateway mobile services switching center (GMSC) and accordingly are respectively referred to as GMSCs 26A-26C.
Each gateway node GMSC 26 serves as an interface to external domains 20 for one or more mobile services switching centers (MSCs) 40 which belong to the domain.
Although any given domain likely has a plurality of MSCs 20, only a single MSC 40 is shown in domains 20 for purposes of illustration. Each GMSC 26 is connected to the MSCs 40 in its domain; MSCs 40 in the same domain may also be connected. Each MSC 40 in FIG. 1 is connected to serve at least one and preferably a plurality of base station controllers (BSCs) 50. For example, MSC 40A serves base station controllers 50A-1 through 50A-m; MSC 40B(1) serves base station controllers 50B(1)-1 through 50B(1)-m. It should be understood that, typically, differing MSCs 40 serve a differing number of base station controllers 50. The use of BSCs 50, shown in the Figures, is for purposes of illustration. It will be recognized that each MSC 40 can directly serve the BSs 60 without any intermediary BSCs 50 in some mobile systems (e.g., TDMA according to IS-136).
Each base station controller 50 is connected to one or more base transceiver stations (BS) 60A-1 through 60A-l(q). The number of base transceiver stations (BS) 60 per base station controller 50 can vary.
Each base transceiver stations (BS) 60 transmits and receives radio frequency communications to and from a plurality of mobile subscribers (MS) 70 in the geographical areas served by the respective BS 60. For sake of simplicity and illustration, only one mobile station 70 is shown in FIG. 1, although it should be understood that each domain 20 serves hundreds if not thousands of unillustrated mobile stations. The particular mobile station 70 depicted in FIG. 1 is shown as being served by base transceiver station (BS) 60A-m(q).
Mobile telecommunications domains 20A-20C each include respective databases 30A-30C. Databases 30A-30C are connected to and maintained by service management systems 32A-32C, respectively. Service management systems 32A-32C are connected to and supervised by a master management system 32M.
Databases 30 are subscriber location servers which are augmented with additional intelligence and are known as mobile subscriber number portability databases. Databases 30 include information which facilitates number portability for many types of subscribers in their respective domains, including mobile subscribers.
As will become more apparent below, the mobile telecommunications domains 20A-20C described above comprise a mobile subscriber number portability domain. In the number portability domain, mobile subscribers can change service providers, e.g., change from one of the domains to another, e.g., change from domain 20A to domain 20C, and still maintain their "directory" number. FIG. 2 shows the circumstance where mobile subscriber 71 has changed service providers. In particular, as depicted in FIG. 2, mobile subscriber 71 has changed his subscription from the provider which operates domain 20C to the provider which operates domain 20B. In fact, at the time shown in FIG. 2, mobile subscriber 71 is served by MSC 40B(1).
Upon the change of subscription as depicted in FIG. 2, deletion of the subscriber (owning mobile station 71) from MSC 40C was communicated to service management system (SMS) 32C, which advised master service management system (SMS) 32M. SMS 32M subsequently communicated the deletion of the subscriber to all SMSs 32, including SMSs 32A, 32B, and 32F, which in turn updated respective databases 30A, 30B, 32F, accordingly. Then, when the subscriber joined the service provider which operates domain 20B, SMS 32C advised master SMS 32M of the enlistment. SMS 32M subsequently advised all SMSs 32 of the enlistment in domain 20B of the subscriber, including SMSs 32A, 32C, 32F, which in turn updated respective databases 30A, 30C, and 30F, accordingly. Therefore, in accordance with the above process, the subscriber of mobile station 71 is able to retain the same directory number upon changing service providers from domain 20C to domain 20B.
FIG. 2 further shows placement of a call from mobile subscriber 70 in domain 20A to mobile subscriber 71 which has changed from service provider 20C to service provider 20B. The originating MSC 40A receives the mobile subscriber call via BS 60A-m(q) and BSC 50A-m. Then, in accordance with conventional techniques, MSC 40A initiates a number portability request message (Action 3-1; FIG. 2), such as, for example, the Number Portability Request Invoke message utilized in ANSI41, to number portability database 30A. However, in view of the previous updating of database 30A to reflect the mobile subscriber 71 changing service providers (as discussed above), the parameter returned by database 30A at action 3-2 includes the address of the new GMSC 26B, not the address of the old GMSC 26C. Thus, at 3-2, number portability database 30A initiates a number portability return message, such as, for example, the Number Portability Request Return Result (npreq) utilized in ANSI41, to the originating MSC 40A. This return message includes a local portability routing number (LRN) to GMSC 26B. Thus, MSC 40A can then connect the originating call from mobile subscriber 70 to GMSC 26B, and thereby to MSC40B(1), BSC 50B(1)-1, BS 60B(1)-1(a), and finally to called mobile subscriber 71. Therefore, mobile subscriber 70 is able to call mobile subscriber 71, which has changed service providers from 20C to 20B, using the same directory number.
Thus, as described above, a call-originating domain accesses a mobile subscriber number portability database to obtain the address of the gateway node of the telecommunications domain which currently serves a called mobile subscriber. Use of the Number Portability database will therefore advantageously permit a mobile subscriber in a telecommunications system to retain the same directory number whenever the subscriber changes from one service provider/operator domain to another service provider/operator domain.
Conventionally, however, the above described number portability database is usable only for telecommunication service providers and does not provide portability towards Internet service providers. Applying conventional number portability techniques to the portability of Internet addressing would be advantageous since both current and proposed (IPv6) Internet addressing systems are provider-based and therefore, whenever a subscriber changes providers, the subscriber's domain name changes as well as the subscriber's IP address. Therefore it would be desirable to extend application of the number portability database to permit a subscriber to change from one Internet access provider to another access provider without changing the subscriber's Internet IP address and/or domain name. Additionally, number portability can be applied to the internet service provider itself. Thus, if an internet service provider's IP address changes, then number portability can permit continued access by subscribers and/or other data communication network. Extending application of the conventional number portability database to Internet service providers therefore advantageously permits a cohesive integration between telecommunication and data communication networks. This integration would permit telecommunication network operators and data communications providers (e.g., internet service providers) to improve service to their subscribers by providing access between the two in a transparent fashion (i.e., telecom to datacom or datacom to telecom). Extending application of the conventional number portability database to internet service providers additionally permits number portability between data communications providers (i.e., datacom to datacom).